Exploding

The best answer so far, at least in my
opinion as a non lawyer, is Sun's community development license.
Basically this is a have your cake and eat it too deal: developers keep
proprietary code proprietary, participate in the free as in freedom
world being built up around openSolaris, and work inside a patent
umbrella held up, not just by Sun, but by mutual agreement among
participating developers. In other words, Joe developer can adopt
openSolaris and the CDDL ( Common Development Distribution License)
without spending a nickel on legal fees and be reasonably confident
that not doing something criminal (or just criminally stupid) will
suffice to protect himself from legal action.

Combine the CDDL with the fact that Solaris is the best OS around, and
it's easy to see why the openSolaris community is exploding ...